The use of hypodermic syringes for administering medications to patients has been known for a relatively long period of time. Over the years, however, physicians have attempted to modify and refine the basic design of the syringe in effort to improve the technique of administering medications to patients.
One of the problems frequently encountered in using a conventional hypodermic syringe is that it often becomes desirable, as well as sometimes necessary, for the physician to operate the syringe with one hand so that the physician's other hand remains free to perform other tasks. A three-ring, or finger-control, syringe has been developed to facilitate one-handed operation. The conventional three-ring syringe allows the physician to retract and engage the plunger of the syringe to permit one-handed filling, aspirating, and injecting. The three-ring syringe has been useful in facilitating accurate positioning of the hypodermic needle in the patient as well as permitting the administration of precise amounts of medication.
Despite the development of the three-ring syringe, a practical problem still remains. Whenever the medication to be administered to a patient exceeds the capacity of the conventional three-ring syringe, the syringe must be refilled during use in order to administer the proper amount of medication to the patient. For example, a conventional three-ring control syringe for injecting a regional anesthetic may have a capacity of approximately 10 cc's. However, many regional anesthetics, such as axillary blocks, interscalene blocks, and femoral-sciatic nerve blocks, require an injection of 30 to 60 cc--s of anesthetic. Since it is not always convenient or practical to use a syringe having a sufficiently large capacity, the conventional practice is either to disassemble the needle from the syringe or to withdraw the needle entirely from the patient to permit refilling of the control syringe. Unfortunately, the conventional practice of disassembling the needle from the syringe results in an increased risk of contamination as well as the added inconvenience and danger of trying to reassemble the refilled syringe to the needle while the needle remains in the patient. Similarly, the conventional practice of withdrawing the needle from the patient to permit refilling of the syringe also increases the risk of contamination as well as the possibility of an accidental needle stick during needle removal or reinsertion.
In accordance with the present invention, a closed system of administering medication is provided that obviates the need either to disconnect the needle from the control syringe or to remove the needle from the patient in order to refill the syringe to administer medication in volumes greater than the capacity of the control syringe. The present invention provides a syringe apparatus and method for administering medications to patients with improved safety to both the physician and the patient.